The present invention relates to an image forming method, an image forming apparatus, and a developer material used with said apparatus.
In recent years, image forming techniques, which are employed in copiers, printers, facsimile machines, and the like, have progressed markedly. Of these, the most frequently employed technique relates to an electrostatic image forming method represented by the conventional electrophotographic system.
The reasons for this progress are considered to be as follows. The electrostatic image forming methods, such as an electrophotographic system and the like, are capable of producing high quality images at a high speed, are capable of forming color images in addition to monochromatic images, and exhibit durability as well as stability over an extended period of time.
In said electrophotographic system, after charging the entire surface of a so-called photoreceptor, exposure corresponding to an image to be formed is provided and an electrostatic latent image is formed. Then the resulting electrostatic latent image is visualized employing a toner and thus images are formed.
In recent years, widely employed as electrophotographic photoreceptors have been organic photoreceptors comprising organic photoconductive materials. As compared to other photoreceptors, organic photoreceptors exhibit the following advantages, that is, it is easy to develop materials for organic photoconductors, which respond to various types of exposure light sources, from visible light to infrared radiation; it is also possible to select materials which do not cause environmental pollution; production cost is lower; and the like. The only one defect is that the mechanical strength is not sufficient and during copying or printing a large number of sheets, the photoreceptor surface suffers from wear as well as from abrasion.
Such photoreceptors are prepared employing either of the following methods: an organic charge generating material is evaporated onto an electrically conductive support which is generally comprised of aluminum or an aluminum alloy; a coating composition, prepared by blending an organic charge generating materials and organic polymer resins as the binders with a solvent, is applied onto a support to form a charge generating layer, and onto the resultant charge generating layer, a coating composition prepared by blending an organic charge transport material and an organic polymer resin as the binder with a solvent is applied to form a charge transport layer.
In an electrophotographic apparatus employing the Carlson method, generally, after uniformly charging a photoreceptor, the resultant charge is eliminated by imagewise exposure to form an electrostatic latent image, which is visualized through development employing a toner, transferred to a sheet of paper and the like, and subsequently fixed.
However, all toner particles on the photoreceptor are not transferred and some toner remains on the photoreceptor. When imaging is repeated in such a state, it is impossible to obtain high image quality copies without staining because the formation of latent images is put into disorder due to the residual toner particles. In order to overcome this problem, it is necessary to remove the residual toner. Listed as representative cleaning means are a fur brush, a magnetic brush, a blade, and the like. However, from the viewpoint of performance, structure, and the like, a blade is primarily employed. Generally employed as said blade member is a board shaped rubber elastic body.
As described above, electrical and mechanical external force from a charging device, a development device, a transfer means, a cleaning device, and the like is directly applied to the surface of the electrophotographic receptor. Therefore, durability to counter these forces is demanded. Specifically demanded is mechanical durability against wear as well as abrasion of the photoreceptor surface due to sliding, layer peeling due to impact and the like during corrective action to counter the introduction of foreign matter and paper clogging. Of these, further demanded is enhanced resistance to counter abrasion and layer peeling due to impact.
In order to satisfy the various properties demanded as described above, heretofore, various means have been investigated.
Regarding said mechanical durability, it is reported that surface wear characteristics as well as toner filming characteristics are improved by applying BPZ polycarbonate as the binder to the surface of an organic photoreceptor. Further, Japanese Patent Publication Open to Public Inspection No. 6-118681 discloses that hardenable silicone resins comprising colloidal silica are employed as the surface protective layer of photoreceptors.
However, photoreceptors, which are comprised of said BPZ polycarbonate binder, exhibit insufficient wear resistance properties and thus do not exhibit sufficient durability. On the other hand, the surface layer, which is comprised of hardenable silicone resins containing colloidal silica, exhibits improved wear resistance properties. However, background stain as well as image blurring tends to occur due to insufficient electrophotographic properties during repeated use. Accordingly, said surface layer also exhibits insufficient durability.
As methods to overcome these drawbacks, Japanese Patent Publication Open to Public Inspection Nos. 9-124943 and 9-190004 propose photoreceptors which have, as the surface layer, a layer comprised of resins prepared by bonding organic silicon modified positive hole transport compounds to hardenable organic silicon based polymers. However, in said technique, since the surface layer is hardened, the photoreceptor surface is minimally abraded. As a result, it is extremely difficult to remove moisture which is adsorbed at an ambience of high temperature and high humidity. Thus image blurring results, and paper dust as well as toner filming tends to be produced. As a result, image problems such as streaking or spotting tend to occur.
An object of the present invention is to provide an image forming method in which a photoreceptor, which results in no wear, is employed, and over an extended period of time, consistent images can be formed without causing image problems such as image blurring as well as streaking or spotting.
The present invention and its embodiments will now be described.
In an image forming method in which a latent image on an electrophotographic photoreceptor is developed employing a developer material, and after transferring the resultant developed toner image on a recording material, the residual toner on said photoreceptor is removed, an image forming method in which said electrophotographic photoreceptor comprises an electrically conductive support having thereon a resinous layer comprising siloxane based resin containing a structural unit having charge transport performance and a cross-linked structure, and said developer material comprises a toner which is obtained by suspension-polymerizing a polymerizable composition comprised of at least polymerizable monomers and colorants or a toner which is obtained by fusing at least said resin particles in an aqueous medium.
In an image forming method in which a latent image on an electrophotographic photoreceptor is developed employing a developer material, and after transferring the resultant developed toner image on a recording material, the residual toner on said photoreceptor is removed, an image forming method in which said electrophotographic photoreceptor comprises an electrically conductive support having thereon a resinous layer comprising siloxane based resin containing a structural unit having charge transport performance and a cross-linked structure, and said developer material comprises a toner which is obtained by suspension-polymerizing a polymerizable composition comprised of at least polymerizable monomers and colorants.
Said siloxane based resin, which comprises the structural units having charge transport performance and a cross-linked structure, is preferably siloxane based resin having a compound group having charge transport performance, as its partial structure.
Said siloxane based resin, which comprises the structural unit having charge transport performance and a cross-linked structure, is preferably obtained by allowing an organic silicon compound having a hydroxyl group or a hydrolyzable group to react with a charge transport compound having a hydroxyl group.
In an image forming method in which a latent image on an electrophotographic photoreceptor is developed employing a developer material, and after transferring the resultant developed toner image onto a recording material, the residual toner on said photoreceptor is removed, an image forming method in which said electrophotographic photoreceptor comprises an electrically conductive support having thereon a resinous layer comprising siloxane based resin containing a structural unit having charge transport performance and a cross-linked structure, and a toner employed in said developer material is one which is obtained by fusing at least said resin particles in an aqueous medium.
Said siloxane based resins, which comprise the structural units having charge transport performance, as well as having a cross-linked structure, are preferably obtained by allowing an organic silicon compound having a hydroxyl group or a hydrolyzable group to react with a charge transport compound having a hydroxyl group.
In an image forming apparatus in which a latent image on an electrophotographic photoreceptor is developed employing a developer material, and after transferring the resultant visualized image onto a recording material, the residual toner on said photoreceptor is removed employing a cleaning means, an image forming apparatus in which said electrophotographic photoreceptor comprises an electrically conductive support having thereon structural units having charge transport performance, as well as having a resinous layer comprising siloxane based resins having a cross-linked structure, and a toner employed in said developer material is one which is obtained by fusing at least resin particles in an aqueous medium.